CSS response is sometimes missing when If-Modified-Since header is used

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: Master
• Fix Version/s: 7.1.10 DXP FP13, 7.1.X, 7.2.10 DXP FP1, 7.2.X, 7.2.1 CE GA2, 7.3.10 DXP GA1, Master
• Component/s: Performance > Caching Infrastructure
• Labels:
  • ee-ts
  • liferay-fixpack-dxp-1-7210
  • liferay-fixpack-dxp-13-7110
• Branch Version/s:
  7.2.x, 7.1.x
• Backported to Branch:
  Committed
• Fix Priority: 4
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/75429

This issue applies for both CSS and JS resources.

Steps to Reproduce (Using Tomcat)

1. Startup Liferay
2. Delete cache files in [TOMCAT_HOME]/work/Catalina/localhost/ROOT/aggregate/
3. Run the following curl command in terminal:

   curl -v "http://localhost:8080/o/dynamic-data-mapping-web/css/main.css?browserId=other&themeId=classic_WAR_classictheme&minifierType=css" -H'If-Modified-Since: Tue, 1 Jan 2222 00:00:00 GMT'
   

4. Observe results from the curl command

Expected Results
Curl result contains a commented timestamp + css content

Actual Results
Curl result contains only a commented timestamp